Skip to main content

Full text of "The Cambridge Natural History"

See other formats

x                             HORNLESS  EXTINCT FORMS                        259
name denotes/ had also canines and, in one species, six incisors
in the lower jaw. This ^Lceratheri'itm had, moreover, four toes in
the fore-feet. In the Miocene and later the Hhinoceros existed in
Europe and America. There was even a purely northern form,
the It"k. ticfaorJiinus, which possessed a woolly covering and had
the same range as the Mammoth. This Rhinoceros was two-
The post-Pliocene and European ElasmotJierium was a colossal
rhinocerotine creature. This great beast had two horns and a
body 15 feet long. Its limbs are not known, and as the teeth
are different from those of Rhinoceroses in general, it may not
have belonged to this group at all, though Osborn is inclined
to derive it from A.ceratlieriutti3 admitting at the same time that
the evidence is " decidedly slender." The teeth in fact are like
those of a Horse in being bypselodont and prismatic in form. As
to the two horns, they were apparently not exactly like those of
typical Rhinoceroses; there was an enormous horn posteriorly,
supported on a huge boss of bone, and in front of this a roughened
spot suggests a smaller or at least a much more slender horn.
It is important to notice that fossil Hhinoceroses belonging to
the restricted genus ^Rhinoceros were in Europe invariably two-
horned ; it is only in India, where they still exist, that one-horned
forms are met with in a fossil state.
The [Rhinoceroses of America were mostly hornless. Dicera-
therium is an exception ; but in many cases it had two parallel not
successive horns, and these were, to judge from the slight promi-
nences, but feeble in development, and perhaps hardly exactly
comparable with the formidable weapons of the Old-World forms.
^Lceratheriu'm tridcwtylum, with indications of paired horns, may
be ancestral to Diceratherium. The American forms have weak and
slender nasals in correspondence with the absence of horns; the
sagittal crest is retained in contradistinction to the great flattened
surface of the skull in the horned Rhinoceroses. A.ceratherium of
both divisions of the globe probably represents the ancestral group
of the horned and the hornless forms. This being the case it is
highly interesting to note a distinct convergence in the quite
1 Quite recently, however, a species, A. in&isivum, preserved at Darmstadt,
lias been found by Professor Osborn to possess- a slight rugosity upon, the frontal
bones, which probably indicates the presence of a rudimentary horn, and tke same
author is apparently inclined to place in Aes&ra^i^irium, the homed
(see p. 261).